The work presented in this paper is motivated by a desire to understand the similarities and differences between various evaluation approaches or theories. As previously argued by Shadish (1998), we believe that such an understanding has value for practitioners, theorists, and those who study evaluation. Our basic premise is that visual depictions of such approaches may help to clarify their most important features, in the same way that logic models are frequently used to explicate program theories. Once the salient features are identified, it becomes more evident what particular combination of evaluator and stakeholder activities constitutes the approach. In addition, an underlying logic is revealed, including an explanation of the ways in which those activities might relate to particular effects or consequences. This may help practitioners who, for example, desire to follow a particular theorist's prescriptions. Miller (2010) has suggested that one way in which we might assess the quality or usefulness of evaluation theories is on the basis of their operational specificity. It is well known that constructing a program logic model can sometimes reveal a less-than-fully-formed program logic. There may be similar value in depicting evaluation theories, as such efforts could help identify those aspects of a theory that are in need of further development. Finally, we believe that creating these visual representations may aid research on evaluation. The models we present here include suggestions and claims about the settings or circumstances in which an approach might be followed, the activities that should be implemented, and the effects that may be expected. From these suggestions and claims, it is possible to identify countless questions that could be examined in future empirical research. Indeed, comparing the existing research base with the assertions made in these models could inform the development of a research agenda, in which certain questions are prioritized on the basis of their relevance to theories of practice. This would allow these theories of evaluation to be tested and, over time, refined.
Background
A (borrowed) framework for modeling evaluation theoriesAs an organizing framework for our visual depictions of the three evaluation theories, we adapted a logic model template developed by the Program Development and Evaluation Unit at the University of Wisconsin-Extension (UWEX). Details of this model are described in a logic model training manual by Taylor-Powell and Henert (2008). Its core elements-including activities and outcomes-resemble those of other common logic model frameworks Evaluation and Program Planning 38 (2013) Here, we describe the development of logic models depicting three theories of evaluation practice: Practical Participatory , Values-engaged (Greene, 2005a, and Emergent Realist . We begin with a discussion of evaluation theory and the particular theories that were chosen for our analysis. We then outline the steps involved in constructing the models. The theoretical prescript...